At Fairplay SH 9 leaves US 285 to head northwest, following the middle fork of the South Platte most of the way to Hoosier Pass where it crosses the Continental Divide 11,532 ft (3,515 m) above sea level.

Switchbacks drop the highway to the Blue River which it follows north through Breckenridge to Dillon Reservoir.

The highway goes around the west side of the reservoir, through Frisco and joins I 70 as it heads northeast.

At Silverthorne, SH 9 leaves I 70 to continue northwest alongside the Blue River.

[2] In 2016, the state completed a wildlife crossing project to reduce wildlife-vehicle collisions between Green Mountain Reservoir and Kremmling, including 2 wildlife overpasses and 5 underpasses; the state also widened the road and shoulders.